Various types of methods or means for separating and destructing injurious substances contained in polluted water or gas exhaust have been studied up to the present, and there also are various types of methods put into practice.
In the methods above, chemical methods comprising adding chemicals into or bringing them in contact with the polluted water or gas exhaust to decompose the injurious substances, biological methods characterized by treating the injurious substances with microorganisms, and electrochemical decomposition methods are mainly known.
However, from the viewpoint of efficiently treating a large quantity of polluted water from ponds, lakes, lagoons, rivers, etc., or from the viewpoint of completely separating and destructing the fertilized algae and predatory small animals or fungi and the like that live on them, or from the viewpoint of decomposing organic compounds recently attracting much attention as serious problems of environmental hormone substances such as trihalomethanes, tributyltin, etc., the methods above all have both advantages and disadvantages. Thus, there has been found a problem that none of the methods above is applicable as a generalized means or method.
More specifically, although an oxygen radical treatment technique for decomposing polyphenols and trihalomethanes using titanium oxide and UV radiations has been developed, there is a problem that the cost of running the method is too expensive due to a low photon efficiency of the UV radiation. Concerning the method for removing blue algae from wastewater, a pressure flotation method has been developed. However, this method not only suffers high operating cost due to the use of flocculants, but also has technological limits such that a high removal ratio exceeding 95% cannot be achieved. Furthermore, this method does not provide a comprehensive solution for the removal of soluble COD.
In light of the aforementioned circumstances, the inventors of the present application have found that the use of a high electric field pulse discharge for the oxidative decomposition treatment is effective, and studies have been made on a desirable method of applying the oxidative decomposition and on the apparatus therefor.